[keycloak-dev] Pushed docs for adapters clustering

I've pushed docs for adapters clustering and support for store account info in cookie https://issues.jboss.org/browse/KEYCLOAK-702, which seems to be last major thing for clustering support on adapters side required for release. I am out tomorrow on public holidays, but back on Wednesday ready to help with whatever is needed for release (there is some probability to being stucked on portal again, but hopefully not...) Marek